Worksheet Science Process Skill | PDF - Free Printable

Problem Analysis:

The task involves separating a mixture of salt, sand, and water using basic laboratory techniques. The goal is to isolate the salt from the mixture by dissolving it in water, filtering out the sand (which does not dissolve), and then evaporating the water to recover the salt.

Solution Explanation:

#### Step-by-Step Procedure and Observations:

1. Mixing Salt, Sand, and Water:
- Procedure: Add 5 grams of a mixture containing salt and sand to 250 mL of water in a 250 mL beaker glass. Stir gently.
- Observation: The salt dissolves perfectly in the water, while the sand does not dissolve and remains as solid particles.
- Explanation: Salt (sodium chloride, NaCl) is soluble in water, meaning it forms a homogeneous solution when mixed with water. Sand, being an insoluble solid, remains undissolved and can be separated later.

2. Filtering the Mixture:
- Procedure: Filter the mixture into a conical flask using a funnel and filter paper.
- Observation: The sand left in the filter paper because the particle size of sand is bigger than the pores of the filter paper, preventing it from entering the beaker perfectly.
- Explanation: Filtering is used to separate solids from liquids based on particle size. The sand particles are too large to pass through the pores of the filter paper, so they remain on the paper, while the salt solution passes through into the conical flask.

3. Evaporating the Salt Solution:
- Procedure: Pour the filtrate (the liquid that passed through the filter) into an evaporating dish and heat the salt solution gently until it starts to "rustle" (boil).
- Observation: The water will be evaporated, and the compound left in the evaporating dish will be white in color and still a little watery.
- Explanation: Heating the salt solution causes the water to evaporate, leaving behind the dissolved salt. As the water boils off, the concentration of salt increases, and eventually, the water is completely removed, leaving only the salt crystals.

4. Turning Off the Heat and Drying the Salt:
- Procedure: Turn off the spirit burner and let the salt dry.
- Observation: If the salt dries fully, it means that the residual compound is pure salt.
- Explanation: After heating, the salt may still contain some moisture. Allowing it to cool and dry ensures that all the water is removed, leaving behind pure salt crystals.

Final Answer:

The procedure successfully separates the salt from the sand and water mixture. The salt is recovered as a pure, dry compound after dissolving it in water, filtering out the sand, evaporating the water, and allowing the remaining salt to dry.

Boxed Final Answer:
\[
\boxed{\text{The salt is recovered as a pure, dry compound.}}
\]